Water-based insulation systems for fire resistant safes have many disadvantages that have gone unsolved throughout the decades of their use. Excess water, desirable for insulation purposes, tends to evaporate out of the insulation, reducing its effectiveness with passing years. This prevents a safe manufacturer from guaranteeing long-term fire resistance. Moisture escaping from the insulation also corrodes the steel cabinets that are necessary for the structural integrity of larger safes. The insulation material has a soupy consistency when initially poured into the safe; and it unavoidably splatters, spills, or leaks onto the safe body, from which it must be cleaned at considerable expense. The outer surfaces of steel safe cabinets cannot be finished before being filled with insulation, because spills and cleanup would mar the finish. The outer surface finish, applied after the insulation is in place, cannot be baked or cured at high temperatures, because the insulation absorbs heat. This reduces the available finish alternatives.
We have discovered that these problems can be solved by forming the insulation within vapor-tight resin molds that can later be assembled into the steel body and door cover of a fire resistant safe. The extra expense of the insulation molds is more than offset by reducing the cost of steel fabrication; eliminating insulation cleanup; allowing use of exterior finishes that are baked at high temperatures; and, most importantly, prolonging the insulation's fire resistance by sealing in its moisture.